Thermostatic control mechanism



Feb. 28, 1950 W. C. EDEN El' AL THERMOSTATIC CONTROL MECHANISM FiledAug. 2, 1946 W/LL/AM C. EDE/V 1N VEN TORS RLro/v w BONDURANT www@ATTORNEYS 'Patented Feb. 28, 1950l THERMO-STATI() CONTROL MECHANISMwilliam c. Eden. am cleveland, and Carlton W. Bondurant, Euclid, OhioApplication August 2, 1946, Serial No. 688,152

` s claims. (ci. zoo- 137) 1 This invention relates. to improvements inthermostatic control mechanism. While the in- .vention is susceptible ofmore or less general ap'- plication, the illustrated embodiment isintended primarily for regulating means for heating liquid .in acontainer so as to maintain its temperature constant within closelimits. The mechanism may be set however to operate at any selectedtemperature within a given range.

One of the objects of the invention is the provision of mechanism of thecharacter stated which shall be of simple construction and yet sensitiveand accurate in operation.

Another object is the provision of means to prevent damage to theworking parts in the event that the apparatus is subjected to atemperature considerably higher or lower than that at which themechanism is intended to operate.

Another object is the provision of mounting means for an electric switchand a switch operating lever which shall maintain those parts in thesame relative position throughout a considerable range of temperatureadjustment.

Other objects and features or novelty will appear as we proceed with thedescription of that embodiment of the invention which, for the purposesof the present application we have illustrated in theaccompanyingdrawing, in which Fig. 1 is a plan view partly in horizontalsectionfshowing our control mechanism attached to a side wall of aliquid container.

Fig. 2 is a vertical sectional view taken substantially on the line 2-2of Fig. 1.

Fig. 3 is an outer end view, partly in section approximately on the line3-3 of Fig. 2.

Fig. 4 is a view partly in section approximately on the line 4-4 of Fig.2.

Fig. 5 is an inner end view of the unit looking in the directionindicated by the line 5-5 of Fig. 2, and

Fig. 6 is a wiring diagram.

In the drawing III represents a side wall of a liquid container, thecontents of which are to be maintained at a selected temperature,generally a temperature above room temperature. The apparatus includes acasing for the control mechanism, and this casing preferably is formedpartially of a casting which provides an upper wall 2 having a bore I8which extends into the interior of the casing. At one end post I'l iscounterbored to receive an end of a tube I9 which constitutes oneelement of the thermostat. Tube I9 and post I'I are held together bysuitable means such as a snug iit and a line of solder 2U.

In mounting the apparatus upon a liquid container, a hole is boredthrough a side wall of the container and the post I1 is projectedthrough that hole. A nut 2I is then applied to the threaded post, apacking ring 22 being disposed between the casting and the containerwail. When the nut is turned up tightly the apparatus will be securelyfastened to the container and the latterwil be sealed against the egressof liquid.

The other extremity of tube I9 is open when the parts are assembled, andthe rod 24 of the thermostat may be inserted through it. This rod isthreaded at one end as shown at 25 in Fig. 1 to receive a nut 26. Thisnut is turned down more or less, depending upon the particular useintended for-the unit, and is then soldered to the tube as indicated at21.

The casting II, I2 comprises a pair of spaced i webs 28 which join thewalls II and I2, and at their inner ends are widened to form bearingblocks 29. These blocks are bored to take a pintle 30, upon which ispivotally mounted between the blocks a bell crank lever 3| having a longarm 32 and a bifurcated short arm 33. One end of rod 24 enters thecasing and is iiattened as shown at 25. A short pin 34 projects throughthe bifurcations 33 of the bell crank and the ilattened end 25 of therod to form a pivotal connection between these two parts.

On the pintle30 outside the blocks 29 there are pivotally mounted theside walls of a sheet metal bracket 35 which is U-shaped incross-section, as clearly indicated in Fig. 3, the cross member of the Ubeing relatively short, as indicated at 36 in Fig. 2. Bracket 35provides the mounting means i'or a switch housing 31 which may besecured to the parallel walls of the bracket by fastenings 3B. Aconsiderable space is provided between the housing 31 and the crossmember 36 of the bracket.

The long arm 32 of the operating lever vworks l within this space, andthe free end of the arm is beveled oil at 39 in order to increasethepossible throw of the lever. The tube I9 is formed of metal with a highcoefficient of expansion, brass` for example, while the rod 24 has arelatively low coeiiicient of expansion; being formed for example ofInvar. An increase in temperature expands the-tube I9 and exerts a pullon the rod 24, which swings bell crank lever 3'I clockwise,

causing it topress on a button projecting from the switch housing. Thispressure opens the switch. The switch being open, a decreaseintemperature contracts tube I9 which causes rod 24 to push against theshort arm of the bell crank.

moving the latter counterclockwise or away from 42 can move bracket 35counterclockwise is limitedtby abutment means in the form of a pin 44,-which is threaded in wall I I and 'engages the cross member 36 of thebracket. We cover wall I I with A cable containing conductors 66 and 66may .enter the casing from one side through an opening I6.' and a cablecontaining-conductors 68 and 10 may enter from the opposite side throughthe other opening I5. The casting is providedwith tapped holes 11 toreceive'setscrews for securing these cables in place.

The walls of the casing, other than the walls II and I2 formed by thecasting. may be of sheet metal attached to the casting by fastenings 15or otherwise. In order to hold the block 51 in position lips 96 and 61are struck up from certain of the sheet metal walls of the casing.

The operation of the unit, it is believed, will be obvious to thoseskilled in the art. The unit '.may be employed in various connections,one

a sheet metal plate 46 attached to the wall by fastenings 46 andprovided with graduation marks 41 surrounding a hole 46 in the platethrough which the pin 44 projects. Above the plate 45 there is securedto a reduced diameter outer portion of pin 44 a turn button 49 with a.pointer 5I) which passes over the graduation marks 41 in swinging fromone position to another. 'Ihe turn button may be secured to the pin 44by a setscrew 5|. A spring 62 surrounding the pin and compressed between-the turn button and the plate 45 serves to exert a pull on the pinsuillcient to prevent any lost motion when the direction of rotation ofthe pin is reversed. The spring also adds friction tending to preventaccidental movement of the turn button. 'I'he graduation marks 41mayindicate degrees of temperature. A pin 63 set into, the wall II servesto limit the movement of the turn button to an arc somewhat less than360. Adjustment of the turn button 49 moves the switch button "toward oraway from the long arm 32 of the operating lever, and thus regulateswithin a limited range the temperature at which the switch is opened orclosed. Obviously the arm 32 of the lever may swing a considerabledistance tc the left, as viewed in Fig. 2, without aiecting the switchin any way, while movement to the right from the illustrated positionafter operating the switch merely swings the whole bracket and switchassembly away from abutment 44 against the action of spring 42. Hencepossible damage to the working parts because of excessively hot or coldclimates, such as might be encountered in shipment of the unit, iseffectively prevented. Connections for electrical conductors enteringthe switch housing $1 are indicated at 55 and 56.

For convenience in making the necessary electricalconnections we providea block 51 of insulation having three sockets 56, 59 and 6B within whichare mounted metal sleeves 6I for the reception of wires, these sleevesbeing perforated and threaded to take setscrews 62 for mechanically andelectrically joining the wires in the respective sleeves.

In Fig. 6 we have shown a wiring arrangement by means of which controlof a gas heater may be effected. The mechanism may be used however toperform other duties. 65 and 66 are conductors which may be connectedwith line wires, v65 being mounted in socket 58. Conductors 61 and 68extend from the terminals 55 and 56 of the switch housing to the socketssa and so, while conductors 69 and 1I! extend from sockets 59 and 6I!through a solenoid 1I which, when energized, acts through an armature 12to open a valve 13 in a gas conductor 14 which may feed a gas burner forheating the liquid in the container in connection with which theapparatus is employed.

particular application being the maintenance'of a desired temperature ofwater in chicken scalding pans or tanks. The disposition of the controlcasing in a horizontal position with the regulating knob on top isespecially convenient in a unit of this character.

The formation of the casing partially as a casting having two walls uponwhich the moving parts of the unit may be mounted, and embodying a postby which the unit may be mounted upon the container with which it is tobe used,

is a valuable feature of the invention. The provision in this samecasting of openings through which the necessary electrical conductorsmay enter the casing is also useful and important. Furthermore the wholeassembly may be completed before the remaining walls of the casing areattached to the casting, the block 51 being mounted in the sheetl metalpart of the casing before the latter is secured to the casting.

'I'he relative lengths of the tube I9 and rod 24 are so selected, andthe nut 26 so adjusted, that at the middle of the desired range oftemperatures for a particular purpose the long arm 32 of the operatinglever will stand substantially parallel to the rod and tube. At thatposition any movement of the rod 24 in either direction will producemaximum movement of the lever. Since .to the changing angularity of theshort arm of the lever with respect to the rod 24 as the pointer 50moves in one direction 'or the other from the central positionillustrated in Fig. 1. Over and under runs of temperature in service orshipment do not strain the switch or other operating parts, and whennormal operating temperature is reestablished the switch is returned .toits preadjusted position.

Having thus described our invention, we claim:

l. In thermostatically operated control mechanism, an electric switch,an operating lever therefor, a common pivotal mounting for said switchand lever, an abutment to prevent movement of said switch toward saidoperating lever, and yieldable means acting upon said switch exclusivelyfor holding it againstsaid abutment, whereby movement of said operatinglever toward said switch and beyond the point of switch operation willswing said switch about said pivotal 'Y s,4os,oes

s. mounting against the action of said yieldable means.

2. In thermostatically operated control mechanlsm, an electric switch, ahousing therefor, a`

sheet metal bracket having parallel walls between which said housing ismounted. a bell crank operating lever having a long-arm disposed betweensaid parallel walls, said bracket and lever being independently mountedto swing about a common axis, means for holding said bracket againstmovement in one direction, thermostatic means for rocking said lever tooperate said switch, -a

-pivotal connection between s aid thermostatic means and said lever forpositively moving the latter in either direction, and adjustment meansfunctioning independently oi said lever for moving said bracket througha limited arc about said axis 3. In a thermostatica'lly operated controlmechanism, an electric switch, a housing therefor, a sheet metal bracketof U-shaped cross-section between the parallel walls oi which saidhousing is mounted, said housing being spaced from the cross member ofthe bracket, a bell crank operating lever having a long arm disposedbetween said parallel walls, said bracket and lever being independentlymounted to swing about acommon axis, an abutmentA to limit movement oi'said bracket toward said long arm, yieldable means for holding the crossmember of said U-shaped bracket against said abutment, thermostaticmeans for rocking said lever to operate said switch, pivotal connectionbetween said thermostatic means and said lever i'or positively movingthe latter in either direction, and means independent of said lever foradjusting said abut ment and thereby moving said bracket through alimited arc about said axis, whereby movement of said long arm beyondthe point of switch operation will swing said bracket about said commonaxis against the action of said yieldable means.

WILLIAM C. EDEN.

CARLTON W. BONDURANT.

REFERENCES CITED 'The following references are of record in the tile ofthis patent:

